Alsace/Lorraine

Sicambres
Sicilians.

Luxembourg/Pepiniere/Rue de l'Ouest
Luxembourg here refers to the gardens around the Palais du Luxembourg, designed for Queen Mary de Medicis in the early 1600s. Rue de l'Ouest would translate to West Road.

Lanoire/Leblanc
(Fr.) Black/white, respectively. 

lux facta est
(Lat.) Literally, "light was made."

Raphael/Mary
Raphael (1483-1520), Italian painter whose most famous works were done in Rome. The Virgin Mary was a frequent subject of his works.

Jean Goujon/Venus
Goujon (1510-1565/8?), French sculptor; a street in modern-day Paris (Rue Jean Goujon) is named after him. Venus is the Roman goddess of vegetation, Greek goddess of love (Aphrodite).

Hannibal marched on Rome
Hannibal.

Manuel du Baccalaureat
"Book of Bachelor of the Arts"? (I'm very uncertain about this one.)

Racine/Molière
Jean Racine (1639-1699), dramatic poet most well-known for his tragic plays. Molière (1622-1673), reknowned playwright whose plays include Tartuffe and Le Misanthrope.

Marcos Obregón de la Ronde
Vincente Martinez Espinel (1550-1624 or 1544-1634?) was the Spanish novelist/musician/poet who wrote the (possibly semi-autobigraphical) 1618 novel Relaciones de la Vida y Hechos del Escudero Marcos de Obregön, on which some of Gil Blas may or may not be based.

Gil Blas
Or Gil Blas de Santillana, novel (pub. 1715? 1735?) known for its realism and detail, written by Alain René Le Sage (1668-1747).

"he would have liked to own the cross"
Undoubtedly a military medal, though I am unsure which one. Note: the Fahnestock/MacAfee/Wilbour translation adds that this is the "Cross of the Legion of Honor."

Petrarch/Dante
Petrarch aka Francesco Petrarca (1304-1374), Renaissance poet and writer. Dante (1265-1321), another Italian poet.

Odeon
Theatre near the Luxembourg.

Audry de Puyraveau
A revolutionary who supported Lafayette for general of the National Guard, and who helped organize military support for the Revolution. He was later elected to the Municipal Commission (1830) and then to the National Constituent Assembly (1848). [thanks to Lawrence Kwong]

Porte-Sainte-Martin
Theatre in Paris.

Frederick

l'Auberge des Adrets
Looks like the l'Auberge des Adrets is a hotel in Adrets that still offers its services today. But the context refers to it as a play. The hotel was rebuilt in 1653 and is associated with the historical figure Gaspard de Besse (1757-81), known as the local version of Robin Hood. Therefore, it is possible that the play is actually about Gaspard, not the hotel. The village of Adrets is near the Esterel Mountains, which is where Gaspard supposedly did most of his robbing. [thanks to Lawrence Kwong]

Sorbonne
University of Paris, Sorbonne, located on the Left Bank; founded in the 12th century by Abelard.

Guicherat

"a Leonidas or a Spartacus"
Leonidas was King of Sparta (c. 491-480 B.C). Spartacus was a Roman slave and gladiator (note the reference "the bench by the Gladiator" a paragraph later) who led a massive slave revolt (Third Servile War or Gladiators' War) which lasted 73-71 B.C. (side note for the curious: in 1960, Universal Pictures released the film Spartacus, starring Kirk Douglas). Apparently statues of these two men (not Kirk Douglas) reside at the Luxembourg.

"Virgil's nymphs"
Virgil (70-19 B.C), Roman poet. His most famous work is the 12-book Aeneid--patterned after Homer's Iliad and Odyssey--which relates the story of Aeneas, a prince of Troy. Yes, nymphs make an appearance here, though I am not familiar enough with his works to know in what capacity (any help?).

"fawns of Theocritus"
Theocritus (310-250 B.C), Greek poet at the court of the Egyptian king Ptolemy II in Alexandria; known for his invention of the pastoral poem (which idealizes the simplicity of shepherd/rural life) .

Isis
One of the most revered Egyptian goddesses; wife of Osiris; goddess of many aspects, including fertility and protection of the dead. Her identifying hieroglyph depicts a throne.

"Bartholo who exists in Cherubin"
Two characters in Beaumarchais' play "Le Mariage de Figaro." Bartholo (or Bartolo), a doctor, endeavors to prevent the marriage; Cherubin (or Cherubino), a page, cheerfully does his best to ensure the wedding. Note that Enjolras is earlier introduced as someone who is not a Cherubin.

Louis XV.
(1710-1774) Second-to-last king of France before the French Revolution. Ascended to the throne at the age of five upon the death of his great-grandfather Louis XIV. Since Hugo refers to style, note that the style of architecture associated with Louis XV.'s reign is rococo, characterized by lightness, delicacy, and elaborate ornamentation.

"the soldier's cross of Saint-Louis"
Royal and Military Order of Saint Louis (?)